Question

find the value of cos 15​

Answer 1

Answer:

Hey mate here is your answer.......

We know that

cos (a-b) = cos a * cos b + sin a *sin b

cos 15 = cos (45–30)

=> cos 15 = cos 45 * cos 30 + sin 45 * sin 30

=> cos 15 = (1/√2)* (√3/2) + (1/√2)*(1/2)

=> cos 15 = (√3 + 1 )/2√2

Hope it helps ༎ຶ‿༎ຶ༎ຶ‿༎ຶ

Answer 2

cos 15=

cos 15 =cos(45-30)

=cos45.cos30+sin45.sin30

=1/✓2.✓3/2+1/✓2.1/2

=✓3/2✓2+1/2✓2

=✓3+1/2✓2